30 - Hematologic Problems Flashcards
normal platelet count
150-400k
thrombocytopenia count
less than 150k
impaired platelet production can be caused by….
- cancer/disorders
- aplastic anemia
- drugs (chemo +)
- immune thombocytopenia
- infections
- nutrnl deficency/alcoholism
- radiation
incr platelet destruction can be caused by…
- artificial surfaces (hemodyalysis, etc)
- DIC
- heparin
- pregnancy
- thrombotic microangiopathy (TTP, atypcl hemolytc UREMIC synd)
most common cause of accelerated platelet destruction
antibodies
-attacks pltlt when the drug binds to pltlt surface
most common acquired thrombocytopenia
IMMUNE thrombocytopenia [ITP]
ITP results fr
- antipltlt antibodies
- impaired pltlt productn
- T-cell mediated destruction of pltlt
ITP MOA
platelets are coated w antibodies> spleen thinks they are foreign + destroys them w macrophages
platelets normally survive..
8-10 days
possibly causes of ITP
- H.pylori
- HIV
- SLE
thrombotic thombocytopenic purpura [TTP]
-assoc w deficiency of ADAMTS13 enzyme
-w/o the enzyme, unusually large amt of vWF attach to pltlt
»>promotes aggregation
-clotting + bleeding occur at same time
-MEDICAL EMERGENCY
ADAMTS13
plasma enzyme
-breaks down the vWF clotting factr
vWF
von Willebrand clotting Factor
-most important protein-mediating platelet adhesion to damaged endothelial cells
TTP is often assoc w…
hemolytic uremic syndr
TTP is characterized by…
hemolytic anemia
- thrombocytopenia
- neurologc abnormalities
- fever
- renal abnormalities
Heparin Induced Thrombocytopenia [HIT]
- platelet destruction + vascular endothelial injury are immune mediated response to heparin
- life threatening
HIT should be suspected if…
pltlt count falls by more than 50% or falls below 150k
major problem of HIT
venous thrombosis
-arterial thrombosis can occur too
HIT complications
- venous thrombosis
- arterial vascular infarcs> necrosis, stroke, end-organ damage
symptoms of bleeding w HIT are ___ bc…
- unusual
- pltlt RARELY drops below 20k
HIT develops ____ after heparin therapy
5-10 days
HIT MOA
PF4 binds to heparin> then binds to pltlt> pltlt activation> more PF4 released (pos feedback loop)> antibodies are made against PF4-heparin-pltlt complx> removed prematurely fr circultn> thombocytopenia + pltlt-fibrin thrombi
thrombocytopenia clinical manifestations
- mostly asymptomatic
- bleeding in mucosal or cutaneous
- large bullous hemorrahge in buccal mucosa
- bleeding into skin (petechiae, purpura, ecchymosis)
- hemorrhage
bleeding in mucosa examples
nosebleed + gingival bleeding
bleeding into skin (petechiae, purpura, ecchymosis)
MOA
when pltlt count is low, RBC may leak out of blood vssls, + into skin
manifestations that indicate internal blood loss
- weakness
- fainting
- dizziness
- tachycardia
- ab pain
- HYPO tension
manifestations that indicate vascular ischemic problems/vascular thrombosis
- confusion
- headache
- seizure
- coma
prolonged bleeding fr trauma/injury does NOT usually occur until platelets are less than….
50k
spontaneous, life-threatening hemorrhages occur when count is less than..
20k
platelet transfusions are not recommended unless it is below…
10k
ITP lab results
-extreme low pltlt
ITP tests
- IgG assay
- pltlt actvtn functn assay
- H pylori
- hep C
- HIV
- bone marrow biopsy
TTP lab results
-medium decr in pltlt
incr in schistocytes, reticulocytes, LDH, bilirubin
decr in HgB, haptoglobin
TTP tests
- ADAMTS13
- urinalysis for protein, blood
- creatinine
- LDH may help establish diagnosis
HIT lab results
- slight decr in pltlt
- maybe incr in schistocytes
HIT tests
- pltlt activatn functn assay
- PF4-heparin-platelet complex (antigen assay)
when destruction is the cause, bone marrow analysis will show ____.
when decreased production is the cause, bone marrow analysis will show _____.
DSTRCTN: normal or increased megakaryocytes
DECR PRDCTN: absence or decr megakaryocytes
Plasmapheresis is indicated for….
TTP + HIT
……. are indicated for ITP + TTP
- corticosteroids
- rituximab
- splenectomy
- immunosuppressive
ITP tx
-IVIG
-corticosteroids
-rituximab
-splenectomy
-immunosuppressive
-anti Rh
-platelet transfusion
romiplostim, eltrombopag, epsilon-aminocaproic acid
TTP Tx
- plasmapheresis
- corticosteroids
- rituximab
- splenectomy
- immunosuppressive
- *ID + Tx of cause
HIT Tx
- direct thrombin inhibitor (ARGATOBRAN)
- indirect thrombin inhibtr (FONDAPARINUX)
- synthtc thrombin inhibitor (BIVALIRUDIN)
- plasmapheresis
- thombolytic agents
- warfarin
corticosteroids are used to treat ITP bc…
- suppress phagocytic response to splenic macrophage
- depress antibody formation
- reduce capillary leakage
IVIG or anti-Rh are given ITP bc…
- pt is unresponsive to corticostrds or splenectomy
- competes w antiplatlet-antibodies for macrophage receptors in spleen
thrombopoietin receptor agonists that are given to ITP…
-romiplostim
-eltrombopag
»>incr pltlt production
example of immunosuppressive therapy
cyclosporine or cyclophosphemide
if untreated, TTP usually results w…
renal disorder + death
plasmapheresis works by providing TTP pts with _____ + removing_____. it also works w HIT by removing….
ADAM13 + approp vWF,
lrg vWF enzymes that are bound w pltlt.
platelet aggregating IgG fr blood
platelet transfusion is CI with…TTP + HIT
bc it may bind + create more clotting
warfarin for ___ should only be started when ____
HIT
-pltlt count has reached 150k
